Bug or Feature?

[Torsten Rienow]

Hi,

i need to have declare several versions of an api
function/sub like this.
PB will not compile, and returns error 466.
Is there any workaround?


#COMPILE EXE

DECLARE FUNCTION MoveMemory LIB "KERNEL32.DLL" ALIAS "RtlMoveMemory" (lpDest AS ANY, lpSource AS ANY, BYVAL cbMove AS LONG) AS LONG
DECLARE SUB ZeroMemory LIB "KERNEL32" ALIAS "RtlMoveMemory" (BYVAL lpDest AS LONG, BYVAL numBytes AS LONG)

FUNCTION PBMAIN

END FUNCTION


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[Guest]

Download the latest win32 API file. It contains Movememory wrapped into a CopyMemory function. Currently, you can't declare the same API function name (in quotes after alias more than once so a work-around is necessary.

[Michael Mattias]

To answer the question, "Bug or Feature?":

I think it's a "negative feature."

A negative feature is something which "works as designed" but the design itself is of dubious worth.

Kinda like Microsoft "Bob."

MCM
(And by the way, allowing multiple declarations of same-aliased external functions would be a terrific new feature.)

[Cecil Williams]

Hmmmmmmmm, PB with overloaded function capability? Sounds like
an outstanding idea.

Cheers,
Cecil

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[Paul Dwyer]

can't you use an #ifdef type idea or do you need to use them both together?




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Paul Dwyer
Network Engineer
Aussie in Tokyo

[Wayne Diamond]

One workaround - change the second declare of "RtlMoveMemory" to something like "RtlMoveMemor2". Compile, use a hex editor, and rename it back.
It seems to work fine when I just tested it with Beep(), but I'm not sure if there are any negative implications in doing this.

Best of luck,
Wayne


[This message has been edited by Wayne Diamond (edited October 22, 2001).]

[Michael Mattias]

can't you use an #ifdef type idea or do you need to use them both together?

Where the "multiple declarations sharing a single alias" would be most useful is when you have a WinAPI function which accepts a variable number of parameters.

DECLARE Function FooWithOne Lib "WHATEVER" ALIAS "WinApiFunc" (parm1) AS LONG
DECLARE FUNCTION FooWithTwo Lib "WHATEVER" ALIAS "WinApiFunc" (parm1, Parm2) AS LONG


   CALL FooWithOne (X)
   CALL FooWithTwo (X,Y)

I forget off the top of my head which functions work like this, but I know there are some. (Wsprintf?)

Also useful for overriding a datatype..

DECLARE FUNCTION FooLong  Lib "whatever" ALIAS "Foo" (X AS LONG) AS LONG
DECLARE FUNCTION FooDword Lib "whatever" ALIAS "Foo" (X AS DWORD) AS LONG

  Z = FooLong (2&)
  ZZ = FooDword (2???)

As long as the target routine is only looking for "32-bit anything" either version should work.


MCM

[Borje Hagsten]

Can also do own ZeroMemory, like:

  POKE$ lpDest, STRING$(numBytes, 0)

Otherwise, maybe possible to place second declare in a separate DLL?


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[Eric Pearson]

A UNION would also be an easy way to do this. Create a UNION with all of the different ways you want to pass values to the API, then change the API declaration to accept a TYPE that contains the UNION.

-- Eric


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Perfect Sync Development Tools
Perfect Sync Web Site
Contact Us: mailto:[email protected][email protected]</A>

[This message has been edited by Eric Pearson (edited October 22, 2001).]

[Fred Oxenby]

Why not use "loadlibrary" and define functions the way "You" want them?


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Fred
mailto:[email protected][email protected]</A>
http://www.oxenby.se

[Tom Hanlin]

Where the "multiple declarations sharing a single alias" would be most useful is when you have a WinAPI function which accepts a variable number of parameters.

Optional parameters are already supported. See the Win32API.inc declare for wsprintf.


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Tom Hanlin
PowerBASIC Staff